#include<stdio.h>
#include<iostream>
#include<string.h>
using namespace std;
int main()
{
	int x, y;
	cin >> x;
	switch (x / 10)
	{
	case 10:
	case 9:cout << "A" << endl; break;
	case 8:cout << "B" << endl; break;
	case 7:cout << "C" << endl; break;
	case 6:cout << "D" << endl; break;
	default:cout << "E" << endl; break;
	}
	return 0;
}